Motility response to insulin-like growth factor-I (IGF-I) in MCF-7 cells is associated with IRS-2 activation and integrin expression

Breast Cancer Res Treat. 2004 Jan;83(2):161-70. doi: 10.1023/b:brea.0000010709.31256.c6.


In MCF-7L cells, insulin-like growth factor-I (IGF-I) stimulates activation of insulin receptor substrate-1 (IRS-1) and enhances cell proliferation. While others have shown that IGF-I enhances cell motility in MCF-7 cells, we have not been able to demonstrate this. To determine if the source of MCF-7 cells account for these reported differences, we examined the MCF-7 cells available from the American Type Culture Collection (MCF-7/ATCC) and compared them to the MCF-7L cells maintained in our laboratory. Both MCF-7L and MCF-7/ATCC grew in response to 5 nM IGF-I and 1 nM estradiol. However, only MCF-7/ATCC demonstrated IGF-I stimulated motility. Immunoprecipitation of IRS substrates followed by anti-phosphotyrosine blotting demonstrated that both IRS-1 and IRS-2 were activated by IGF-I in these cells. However, MCF-7/ATCC cells had greater phosphorylation of IRS-2 compared to MCF-7L. Immunoblots showed that levels of IRS-1 and IRS-2 were comparable between cell lines. We have previously shown that fibronectin-binding integrins are necessary for IGF-stimulated motility. Similar levels of beta1 integrin were detected in both strains of MCF-7. However, low levels of alpha5 and alpha3 were detected in MCF-7L cells whereas high levels of alpha3 and alpha5 integrin were expressed in MCF-7/ATCC cells. Inhibition of integrin function by a blocking antibody or inhibitory peptide diminished IGF-mediated motility in MCF-7/ATCC. In MCF-7/ATCC cells, IGF-I stimulation was associated with a movement of IRS-2 to the leading edge of filopodia. Thus, patterns of integrin expression among breast cancer cell lines may partially explain the different motility behavior of cells in response to IGF-I. IRS-2 activation and integrin occupancy are both required for IGF-stimulated motility.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Breast Neoplasms / pathology*
  • Cell Line, Tumor / drug effects
  • Cell Movement / drug effects*
  • Female
  • Flow Cytometry
  • Humans
  • Immunoblotting
  • Insulin Receptor Substrate Proteins
  • Insulin-Like Growth Factor I / pharmacology*
  • Integrins / metabolism
  • Intracellular Signaling Peptides and Proteins
  • Phosphoproteins / metabolism


  • IRS2 protein, human
  • Insulin Receptor Substrate Proteins
  • Integrins
  • Intracellular Signaling Peptides and Proteins
  • Phosphoproteins
  • Insulin-Like Growth Factor I